Prado Dam FIRO Preliminary Viability Assessment
Total Page：16
File Type：pdf, Size：1020Kb
Section 1 Executive Summary .................................................................................. 1 Project Overview ....................................................................................................... 1 Atmospheric Rivers and FIRO ..................................................................................... 2 Results of the PVA ..................................................................................................... 3 Recommendations and Roadmap for the FVA .............................................................. 5 Section 2 FIRO at Prado Dam ................................................................................... 6 Background .............................................................................................................. 6 FIRO Project Objectives ............................................................................................. 9 FIRO Viability Assessment Process and Timeline .........................................................10 Prado Dam FIRO Steering Committee ........................................................................11 Santa Ana River Watershed and Prado Dam ...............................................................13 2.5.1 Meteorology and Climatology ........................................................................ 13 2.5.2 Geophysical Characteristics ........................................................................... 13 2.5.3 Prado Dam Authorization and Current Operations ........................................... 16 2.5.4 Flood Risk Management and Water Conservation ........................................... 17 Operational Constraints ............................................................................................21 2.6.1 Existing Spillway at Elevation 543 Feet .......................................................... 22 2.6.2 Inundation Within the Reservoir .................................................................... 22 Opportunities for Improvement .................................................................................23 2.7.1 Santa Ana River Mainstem Project ................................................................. 23 2.7.2 Enhanced Recharge ...................................................................................... 24 2.7.3 Environmental Considerations ....................................................................... 24 Section 3 How FIRO Viability Was Assessed .......................................................... 26 Evaluation Framework: the HEMP ..............................................................................26 3.1.1 Boundary Conditions ..................................................................................... 27 3.1.2 Metrics 29 3.1.3 FIRO WCP Alternatives ................................................................................. 29 System Modeling Plan ...............................................................................................31 3.2.1 EFO Model for Prado Dam ............................................................................. 31 3.2.2 Simulation of OCWD Diversions and Groundwater Recharge ........................... 38 Simulation Plan ........................................................................................................44 3.3.1 Streamflow Observations .............................................................................. 44 3.3.2 Streamflow Forecasts ................................................................................... 44 Refinements for the FVA ...........................................................................................51 References ...............................................................................................................52 i Section 4 Evaluation of FIRO Water Control Plan Alternatives .............................. 53 Key Findings ............................................................................................................54 Groundwater Recharge Metrics .................................................................................55 Flood Risk Management ............................................................................................59 Environmental Metrics ..............................................................................................64 Conclusions and Recommendations ...........................................................................66 Section 5 Studies, Research, and Development in Support of the PVA ................. 67 Overview and Purpose ..............................................................................................67 5.1.1 Scientific Advances That Contribute to FIRO’s Viability at Prado Dam ............... 67 5.1.2 Research and Operations Partnership: A Blueprint for Success ........................ 68 Meteorological Analysis, Assessment, and Research ...................................................69 5.2.1 Meteorology and Climate of the Santa Ana River Watershed ........................... 71 5.2.2 Predictability of Extreme Precipitation Events ................................................. 71 5.2.3 Regional Models: West-WRF ......................................................................... 73 5.2.4 Meteorological Monitoring ............................................................................. 76 5.2.5 Assessment of AR Recon Benefits and Application .......................................... 78 5.2.6 Supplemental Forecasting Products for Prado FIRO ........................................ 79 Hydrologic Monitoring and Modeling ..........................................................................84 5.3.1 Assessment of Data in the Prado Basin .......................................................... 84 5.3.2 Modeling and Forecasting of Flows into Prado Lake and the Local Contributing Area Below Prado Dam and Recharge Area ............................................................... 88 5.3.3 Ongoing Work and Recommended Studies for the FVA ................................... 91 Environmental Considerations ...................................................................................91 5.4.1 Effects of Flood and Conservation Pool Inundation on Riparian Vegetation ....... 92 5.4.2 Prediction of the Arrival Date of Nesting Least Bell’s Vireos in Future Years ...... 97 5.4.3 Opportunities for Vireo Habitat Mitigation ...................................................... 97 5.4.4 Magnitude and Impact of Increased Sedimentation with Periodic Increases in Water Surface Elevation Above 505 Feet ............................................................... 97 5.4.5 Ongoing Work and Recommended Studies for the FVA ................................... 98 References ...............................................................................................................99 Section 6 Findings and Recommendations ........................................................... 104 Meteorological Analysis, Assessment, and Research ................................................. 104 6.1.1 Findings ..................................................................................................... 104 6.1.2 Recommendations for the FVA .................................................................... 104 Hydrologic Monitoring and Modeling ........................................................................ 105 6.2.1 Findings ..................................................................................................... 105 6.2.2 Recommendations for the FVA .................................................................... 105 Water Resources Engineering .................................................................................. 106 6.3.1 Findings ..................................................................................................... 106 ii 6.3.2 Recommendations for the FVA .................................................................... 107 Environmental Considerations ................................................................................. 108 6.4.1 Findings ..................................................................................................... 108 6.4.2 Recommendations for the FVA .................................................................... 108 Section 7 Roadmap for the Final Viability Assessment ........................................ 109 Coordination, Communication, and Timing ............................................................... 109 Research and Development .................................................................................... 109 7.2.1 Atmospheric River Science .......................................................................... 109 7.2.2 Monitoring and Environment ....................................................................... 110 7.2.3 Hydrologic Monitoring and Modeling ............................................................ 110 7.2.4 Water Resources Engineering ...................................................................... 111 Interim Operations ................................................................................................. 111 7.3.1 Deviations (Minor/Major) ............................................................................ 111 7.3.2 Decision Support ........................................................................................ 111 Appendices Appendix A: Santa Ana River Mainstem Project (SARM) Features Appendix